Designs in place of words repeatedly found in mathematics (7)

I believe the answer is:

formats

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'designs in place of words repeatedly' is the definition.
I can't tell whether this defines the answer.

'found in mathematics' is the wordplay.
'found' becomes 'form' (both can mean to establish or set up).
'in mathematics' becomes 'ats' (I can't explain this - if you can you should believe this answer much more).
'form'+'ats'='FORMATS'

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I've seen this clue in The Guardian.

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